INDIAN DENTAL ACADEMY
Leader in continuing dental education
Narrow maxilla was recognizes for thousand
years and Hippocrates referred to it
A number of crude techniques may be gleaned
from the works of early dental practitioners
Fauchard (1728), Fox (1803), Delabarre (1819),
and many others until
Walter coffin demonstrated the expansion of the
maxillary arch using a spring which caused
separation of the mid palatal suture in children.
In 1860 Emerson c . Angell placed a screw between
maxillary premolars of a girl aged 14 years and widen
her arch in two weeks.
The essential passage read “ this apparatus was placed in
the mouth. when the shaft was made to revolve until the
fixture was made uniformly firm, when the patient was
provided with the key and instructed to keep the shaft as
uniformly tight as possible. These instructions were
industriously followed and at the end of two weeks ,the jaw
was widened as to leave a space between two front incisors
,as indicated in diagram no 2, showing conclusively that
the maxillary bone had been separated whilst the upper
left lateral incisor had been brought outside the inferior
This bold statement introduced what was to go down as
a landmark in dental science and placed Angell ahead of
Great debate of twentieth century
With this started great debate for slow expansion or rapid
Dr E.H.Angle stood for expansion but was against the use of
plates which he said was unhygienic.
His dogmatic approach and such was his influence that all
plated appliance was left for the banded ones even in
American south where crozat were commonly used .
Although fixed plates continued in Europe which was away
from his influence.
In 1939 A.M.Schwarz wrote a textbook on removable
appliances providing others how to use fixed plates .
America was unaware of ad Vance's on removable
appliances as was Europe was to fixed ones.
On The Basis Of Direction
Expansion in lateral direction (unilateral / bi-lateral)
e.g. in treatment of the buccal crossbites
Expansion in the antero-posterior region
(unilateral /bi-lateral )e.g. treatment in anterior cross-bite cases.
Expansion in the antero-posterior as well as in
lateral direction.e.g. “Y” shaped expansion screw
Expansion for distalization of segment of the teeth
of canine and molars
BASIS OF THE EFFECT CAUSED BY THE FORCES
BASIS OF THE APPLIANCE USED
Treatment with them will not
provide the best answer to every
orthodontic problem. Some
small degrees of irregularity are
impossible to treat and some
severe malocclusions respond
Easily designed to produce tooth
movements labio- and buccolingually and mesio-distally.
Removable appliances can be designed easily to produce
tooth movements labio- and bucco-lingually and mesiodistally.
Removable appliances have many advantages they
exert minimal interference with dentoalveolar growth.
They are useful during the developing stages of
Treatment with them at early stages is attractive as it
offers early completion dtes and little inconvenience
during socially and educationally busy years for the
The objective of orthodontic force is to move teeth
individually or in units, using other teeth, both
supported and unsupported, for anchorage .
Orthodontic forces are ideally measured in grams
and ounces, optimum tooth movement occurs with
relatively mild forces, whether they are continuous
They are usually directed toward a small area, such
as the periodontal membrane of a tooth or teeth.
Orthodontic forces are always applied
directly to the teeth, the kineses being
supplied by arch wires, intermaxillary
elastic, intramaxillary elastics, light
extraoral force, bite plates, and other
auxiliaries. It is intended that certain
teeth move while others, hopefully,
conjunction along with
macary activator have
been forgotten but
should be reconsidered
when using functional
Require precise design and accurate
Patient co-operation is must.
Difficult to obtain two point contact
on tooth to obtain complex tooth
Factors important for
design of active plates
Indications :1. upper arch expansion where lateral
expansion is indicated. it can be used in
cases of unilateral as well as bi lateral
2. Antero-posterior expansion required
3. Differential expansion in anterior or
posterior region is desired .controlled
movement can be obtained.
4. When space requirement is less than 3 mm.
Constructed from 1.25mm wire.
Two types can be prepared i.e.
• With the help of universal pliers a generous loop in the
shape of tear or a diamond shape is prepared. It is kept
1 mm away from the palate.
Tags are prepared at the end of the wire to be embedded in
Four Adams clasps are prepared on the first molars and first
molars for retention.
Acrylization can be done with direct method.
Originally the base plate was made in one piece and cut with
fine saw after vulcanization.
Present day practice is to make the base plate in two small
segments, large enough to make contact all the teeth to be
moved and contain the tags of the of the clasp and the wire
It should be seated high up on the
palatal vault to increase
acceptance in patients.
Anterior bends may not be
incorporated in acrylic to permit
full range of action .
As an alternate to screws plates it
is cheaper and less bulky but
unless precise construction and
adjustment these may be rather
Pits are drilled into the base plates allow the initial
width of the appliance to be checked with calipers
.the spring is expanded anteriorly first, then
posteriorly by pulling it apart, care being taken not to
twist the appliance.
This easier and quicker than adjustment with pliers.
An expansion of 2-3 mm
will generally be
Open activators of Klammt it
is combination of the original
activator and bite former. it is
particularly important in
cases of a narrow maxilla
with a distal bite.
Schmuth incorporated a
coffin spring in original
Balters bionator and was
known as functional
kybernator it was small and
could be worn full time thus
all the more effective.
George crozat developed a removable appliance
fabricated entirely of precious metal in 1920 that is
still used effectively.
Fabrication is simple but handling appreciably hard
It consisted of an effective clasp for first molar teeth
modified from the Jackson design. heavy gold wire
for framework and lighter gold finger spring for
It was flexible and superior
than other alternatives
available that time.
Specialist with crozat
appliance can achieve dental
Distal movement of canine,
premolar and molars.
Single tooth movement
including bodily movement
Correction of anterior
crowding and protrusion
Required great effort and
The expansion screw is a very small metallic appliance
which may be designed to move a single tooth or a group of
teeth or the skeletal bases as required. This screw as a
source of force together with the acrylic segment of the
plate effect the teeth and the alveolar process.
Different type of screws may be used advantageously for
certain procedure during treatment with removable
The screw normally transmits its forces by
means of acrylic. Which comes in contact with
The patient usually activates the screw once or
twice a week.
Fairly high force is generated but it is
intermittent in nature.
Desirable features in screw are adequate travel,
stability and minimal bulk.
Screws can be used for various tooth movements
but they add up to the bulk of the appliance
making it bulky.
Screws are useful in antero-posterior and
transverse arch expansion and also in
contracting a wide arch.
Single and double guide pin screws are available
the latter are more stable but requires more space
Problems tend to occur with screws, some tend to
turn back under load.
If the appliance is left out it will not be possible
for the patient to re insert it and treatment may
As activation at any time is small (0.2mm) large
force generated is acceptable .tooth moves within
the limits of the periodontal ligaments and
excessive hyalinization will not be produced .
Spring loaded screws are available but they offer
few clinical advantages.
According to desired action of screw
Expansion screw appliance used to
widen a dental arch.
Appliance with screw to move individual
teeth or small group of teeth in a
buccal or a labial direction .
Appliance with screw to move individual
teeth or small group of teeth in a
mesial or a distal
Positioning of screw
Rules and guidelines for screw positioning: It is positioned in three
It should be placed in the
mid line oriented to median
raphe when bi-lateral
expansion is to be planned
.screw lies on a imaginary
line passing between the first
and second premolar.
In a narrow arch it should
be positioned more
The horizontal plane of the
screw is placed parallel to
the plane of the occlusal
Orientation determines the
line of force not the cut in
With the tag it is positioned
with the arrow pointing in
the right direction. wax is
added to prevent its
Key is inserted in the hole
and when turned .metal end
plates move apart or closer if
closing screw is used
Guide pins prevent the end
plates from rotating and
enhance appliance stability
The screw is not placed
parallel to the palatal vault,
rather it should be turned
about 45* forward so that
child can activate it himself
It is adjusted by only a small
amount at one time due to its
rigidity. otherwise appliance
cannot be inserted.
After teeth move it can be
Pitch of the screw is set so that
the tissue does not get harm
during expansion a complete
turn of 360* will produce a
separation of 0.8 -1mm .
The screw when turned 90*
will produce separation of
That means the periodontal
ligaments gets narrower by
0.1mm on each side. this is a
mil reduction thus do not
cause excessive hyalinization
and also creates ideal
orthodontic condition for the
transformation of the bone.
In children when
expanding 90*turn at each
adjustment is sufficient
and adjustment is made
twice a week.
In adults tooth movement
has to be carried out more
slowly so a 45* turn or1/4th
turn per week is suffiecent
Controlled movement can
Activation can be done at
Various types of tooth
. It is easily available
commercially do not require
skill of the clinician
Can be added to suffix the
Reliance on the patient for
May cause difficulty in
Does not applies a constant
Requires excellent retention
Over- activation may cause
Bertoni screw for selected arch
expansion and for labial
movement of upper incisor
Special screws for
Screw for symmetrical
Distal screw for upper right
Maxillary plate combined with
the three special screws attempt
at anterior movement, distal
movement, and segmental
It is an horse shoe shaped and covers only
anterior and lateral parts of the palate contain
a expansion screw in the middle.
The limits of lower plate is determined by the
height of the alveolar process. This is not so
critical as retention depends on clasps and
appurtenances of the appliance.
These make use of the forces that are in second
degree of efficiency.
To obtain the effect the plate should be secured
in place against the palatal tissue.
An important general rule is that difference
between the force and the counteracting
resistance must be large as possible in favor of
As the screw is turned the plate act as true
orthographic –jaw orthopaedics appliance not
only against the teeth themselves but also
against the lateral walls of the palate.
This capacity of plate appliance to carry
pressure directly to the bony parts of the
arches as well as the teeth may even provide
stimulation to the center of growth along
median palatal suture.
With adjustment of the active plate sore spots are
likely to appear they must be removed by selective
To effect minor tooth movement with active plate,
it is important to remove the peripheral margin
off the appliance next to the coronal portion of the
teeth, usually at the gingival margin.
One must keep in mind that only does the tooth
move , but so do the gingival tissue and the
contiguous alveolar bone
It is wise therefore to reduce the appliance
sufficiently to permit all the tissues to move when
n there is doubt it is always better to remove too
much that too little
A removable appliance impinging on
gingival tissue cause hypertrophy, edema
and pain this need not happen with
proper adjustment if it is desired to
maintain contact after the movement
achieved , restore the exact periphery in
contact with the tooth by adding self
In actually the active plate is limited only
by the imagination of the operator . It
may carry locks, tubes, arches, rotating
springs, habit preventing appliances or
other appurtenances ordinarily
considered to be in the realms of fixed
Lower Schwarz Appliance
This is specific type of active plate used in early
stages of the mixed dentition period, to produce
orthodontic tooth movement in the mandible mainly
uprighting the posterior dentition and increasing
anterior arch length anteriorly
It is rare to use lower Schwarz appliance as
sole appliance to produce tooth movement. It
is used in patients who have arch length
deficiency and/or posterior teeth that have an
abnormal lingual inclination.
McNamara recommends the completion of or
near completion of Schwarz activation prior to
onset of RME , he found that greater expansion
transversely possible if lower teeth were in
proper position at the initiation of RME .
It is cardinal rule of the orthodontics that the
lower canine expansion is relatively unstable, so
why is treatment with this appliance is
Studies carried out by Brust have shown that
that average increase of 2.3mm more in arch
perimeter at the end of therapy in
Schwarz appliance may be useful in patients
with mild to moderate lower incisor crowding
but will not satisfy the arch length requirements
of a patient with severely crowded incisor
This is made from wire and acrylic
Simple ball end clasps are placed in the embrasures
between the lower deciduous molars and lower first
Adams can be used for additional retention usually
Expansion screw is located in the midline and
embedded almost in acrylic.
Additional acrylic also can be placed on the occlusal
surface of the posterior teeth in case in which a
posterior bite block effect is desired.
It is easily manageable clinically. Usually delivered without
Appliance is worn full time first 3-5 month as an active plate
( one mm expansion each month can be expected i.e. mm
every 4 turns) and then as passive one for additional period
of time for retention.
Additional arch length of 3-4mm(mcnamara) can be gained
on routine basis .
Simple and a straight forward technique.
Not recommended in the treatment of gross tooth size/arch
length discrepancy problem.
Saggital appliance develop arches mainly in
antero posterior direction, by moving teeth in
groups or singly.
Screws are placed parallel to the antero
posterior plane or parallel to crest of the crest of
the alveolar ridges.
If second molar is missing the expansion can be
80% in posterior region and presence of second
molar makes the expansion 80 % anteriorly.
When such appliance is used for distalizing
there is slight increase in arch width but this is
The design is dependent on distortion present in
the arch .
Appliance has a basal plate sectioned into three
One braced against prevail and midpalatal area
Two braced against posterior teeth and lingual
gingival areas along posterior teeth on each side
Clasp on posterior teeth for retention generally
Adams on first molars and ball clasp in canine
“ Y “ Plate
It is an active removable type of appliance that
moves the teeth under certain conditions its
appearance is similar to that of the bite plate
and it is anchored on the maxillary arch with
Adams or arrowhead clasps.
The labial bow inserts into the acrylic in the
lateral incisor –canine embrasure
The plate has two jack screws exerts a
The opening of the jackscrews exerts a distalizing
component on the buccal segment teeth and a
reciprocal force is delivered to the anterior palatal
contour and maxillary incisors.
To reduce the mesial force component, which tend to
tip the incisor labialy and dislodge the appliance, the
screws are activated alternately and unilaterally.
First premolars erupted, giving increased anchorage.
Upright incisors and slight tipping not undesirable.
No extensively bodily movement are required.
The second premolar have not yet erupted.
When the forces of the buccal and labial
musculature are shielded from the occlusion , a
widening of the dental arches often occurs.
This expansion is not produced through the
application of extrinsic bio-mechanical but rather
than by intrinsic forces in the dental arch such as
those produced by the tongue.
In the growing child rigid removable
appliance should be avoided, and attempt to
use elastic bi maxillary appliance which
stimulate the activity of oro facial
Balters in this context states “ It is
unnecessary to use active forces for arch
expansion as interplay of muscle takes care of
dental arch formation, it should be realized that
the orthodontics should lead to jaw
orthopaedics i.e.. reforming the jaw and the
dental arches on a functional basis . ”
Frankel has emphasized on the use of labial and buccal
Using lip pads and the buccal shield effectively hold
the buccal and labial musculature away from the teeth
and investing tissue eliminating any restrictive
influence that this functional matrix might have.
Another possible mechanism of arch expansion
involves an aspect of the appliance that has been
continually stressed by frankel.
He has stated that the vestibular shields should be
extended into the vestibular reflex so that the tension
produced on the soft tissue and this pull on the soft
tissue is transferred to the periosteunm and results in
deposition of new bone on the facial aspect of the
VESTIBULAR SCREEN AND
These can be used during deciduous and mixed
Philosophy of these appliances are similar to the
frankel appliance. The change in balance of the
forces between the tongue and peri-oral musculature
causes expansion of the jaws.
Originally developed by
Balters in early 1950 .
Buccinators loops eliminates
the tension of the strong
buccinator muscle thus there
is marked arch expansion .
Coffin spring is not active
but stimulator for the tongue
Activator and headgear
Treating anterior protrusion with spacing and disto
occlusion. A combination of extra oral force must be
It prevents vicious habits and reorient physiological
Act as space maintainer .
Expand not actively but as the teeth move distally
the expansion of the arch takes place because they
move to wider part so to maintain contact the screw
Starts to correct deep bite.( within Freeway space
Helps correct class II relationship in three plane of
Design not very different from ordinary appliance.
Four clasps on teeth usually required, if claspable
teeth not present accessory arrowhead clasp to
produce retention, and allowed to seat firmly to
avoid levering and tipping effect.
This appliance is dynamic functional elastic syste,
activated by muscl energy in transverse and
saggital development of the arches.
It is only indicated in certain cases of narrow arch
with anterior croeding, because the coffin spring is
upper part is not suffiecent to correct the severe
arch compression. but incorporating a screw
makes it more rigid so that the relative forces of
the mandible are not utilized which is why a coffin
spring is used.
Tongue activates the elastic
bite former with coffin spring
Types of corrections using coffin
spring in Bimler appliance
( Class II/I )
( Class III )
Proffit has compared the effects of rapid
maxillary expansion with slower one.
Outlook looks similar after two months
It is maintained that the crowding is attributed to the
lack of arch width.
Expansion of arches will produce the space for
proper alignment of anterior teeth .
Without extraction alignment tends to arrange
anterior teeth into wider circle by means of
proclination of these teeth.
These placements of dental arches are not stable and
from them more or less degree of relapse takes place
in absence of new stabilizing factor.
The main role of expansion is the possibility
of correcting discrepancies in bucco-lingual
Removable appliance should be regarded for
producing expansion of the buccal segment. It
is important to regard this movement as
intended for correction buccolingually of the
Chance of major relapse after expansion
decreases if done slowly during mixed
dentition that brings about the adjustment if
the musculature and tongue space.
Amount of retention is different for different
cases, better to overestimate.
Younger the age more stable the result.
Treatment with removable appliances will
not provide the best answer to every
Ideal rate of expansion : - 1mm /week .
Collapsing forces are prevalent for
approximately 6 months . Over expansion .
Maxillary arch more stable than the lower
arch to maintain space achieved.
Some small degrees of irregularity are
impossible to treat with removable appliances,
and some severe malocclusions respond well.
Nevertheless they are cheap to construct and
hence treatment cost cut down appreciably.
Decision to acquire space by expansion or
other means should be based on the
meticulous assessment of the diagnostic data
and understanding of the underlying etiology
and possible growth mechanism.
As for expansion it has tested
the deep waters of time to be
completely trusted and accepted
as a respected treatment
modality in the field of
Leader in continuing dental education